Safety of conversion from cyclosporine Sandimmune to cyclosporine Neoral in stable liver transplant patients

Impact of cyclosporine on the development of immunosuppressive therapy

With the advent of cyclosporine (CsA) 20 years ago, graft survival increased considerably to more than 80% at 2 years posttransplant. The early formulation of CsA, Sandimmun, is effective in preventing organ rejection, although its absorption profile means it is subject to a high degree of variability. The development of a microemulsion formulation, Neoral, provided a therapy with superior efficacy in kidney, liver, and heart transplantation with an improved pharmacokinetic profile. Calcineurin inhibitors (CNIs), including CsA, have a narrow therapeutic range, so frequent blood measurements to control drug levels are required. Recent research has demonstrated that the measurement of blood CsA concentration at 2 hours postdosing--C2 monitoring--has the potential to optimize efficacy and reduce the side effects associated with CNI use. In heart and de novo kidney transplantation, C2 monitoring may help to further reduce the incidence of acute rejection, while in maintenance renal transplant recipients, C2 monitoring can help to detect overexposure and thus allows safe dose reduction, which may improve blood pressure and renal function. C2 monitoring thus facilitates a better balance between effective Neoral immunosuppression and unwanted side effects. Today, CsA remains the cornerstone of immunosuppression, and ongoing studies aim to further optimize patient management strategies with Neoral. With other trials evaluating the impact of Neoral in combination with newer therapies such as Certican, myfortic, and FTY720, the use of CsA in transplant recipients looks set to continue.

Cyclosporin: an updated review of the pharmacokinetic properties, clinical efficacy and tolerability of a microemulsion-based formulation (neoral)1 in organ transplantation

Cyclosporin is a lipophilic cyclic polypeptide immunosuppressant that interferes with the activity of T cells chiefly via calcineurin inhibition. The original oil-based oral formulation of this drug (Sandimmun)l was characterised by high intra- and interpatient pharmacokinetic variability, with poor bioavailability in many patients; a novel microemulsion formulation (Neoral)1 was therefore developed to circumvent these problems. Studies show increases, attributable chiefly to improved absorption in patients who absorb the drug only poorly from the original formulation, in mean systemic exposure to cyclosporin with the microemulsion, with no clinically significant differences in tolerability or drug interaction profiles. Cyclosporin microemulsion is at least as effective as the oil-based formulation in renal, liver and heart transplant recipients, with trends towards decreased incidence of acute rejection with the microemulsion formulation in some (statistically significant in a few) trials. Cyclosporin microemulsion and tacrolimus appear to have similar efficacy in preventing acute rejection episodes in most renal, pancreas-kidney, liver and heart transplant recipients. However, there are indications of superior efficacy for tacrolimus in some trials, particularly in the prevention of severe acute rejection and in Black transplant recipients. Current 12-month data also indicate equivalent efficacy of sirolimus in renal transplantation. Conversion from the oil-based to microemulsion formulation in stable renal, liver and heart transplant recipients is achievable with no change in acute rejection rates. The addition of an anti-interleukin-2 receptor monoclonal antibody and/or mycophenolate mofetil to cyclosporin microemulsion plus corticosteroids decreases rates of acute rejection; corticosteroid withdrawal without increased acute rejection rates was also achieved on the addition of these agents in some trials. Pharmacoeconomic analyses have shown savings in direct healthcare costs in kidney or liver transplantation when cyclosporin microemulsion is used in preference to the oil-based formulation, although studies incorporating indirect costs or expressing costs in terms of therapeutic outcomes are currently unavailable.

CONCLUSIONS

The introduction of cyclosporin microemulsion has consolidated the place of the drug as a mainstay of therapy in all types of solid organ transplantation; research into optimisation of outcomes through more effective therapeutic monitoring in patients receiving this formulation is ongoing. Several novel immunosuppressants have been introduced in recent years: further clinical and pharmacoeconomic research will be needed to clarify the relative positioning of these agents, particularly with respect to specific patient groups. Other new drugs (basiliximab/daclizumab and mycophenolate mofetil) offer particular advantages when used in combination with cyclosporin.

Neoral use in the liver transplant recipient

This review and critical analysis of current trends of immunosuppression management in liver transplantation provides evidence and support for the continued role of Neoral as an indispensable part of immunosuppressive protocols. CyA formulation influences clinical outcomes such as acute rejection; this is confirmed by several multicenter studies. The CyA microemulsion formulation provides more reliable and effective absorption characteristics, and it may provide more rapid and complete immunosuppression in the de novo patient than IV administration. An advanced TDM strategy, particularly a 2-hour post-dose blood level (C-2), can improve the effectiveness and safety of immunosuppression in de novo liver transplant patients. There are potential risks resulting from CyA withdrawal strategies, as there is no evidence supporting this strategy. Neoral is an indispensable part of combination protocols in liver transplantation.